Stuttering — also called stammering or childhood-onset fluency disorder — is a speech disorder that involves frequent and significant problems with normal fluency and flow of speech. People who stutter know what they want to say, but have difficulty saying it.
Adult-onset stuttering can also be caused by head injuries, brain tumors or neurodegenerative diseases such as Parkinson’s disease and multiple sclerosis (MS). The stuttering in these cases develops as the disease progresses. A number of drugs also can affect the brain’s ability to coordinate the different components involved in speech.